This has been a great car for me but I'm at the end of my rope with this one. Maybe someone here has some insights before I pour more money into it.

I have a 2006 Mazda 3s sedan, with the 2.3L engine and automatic transmission.

Back in December there was one goofy shift around 2nd gear which caused the AT light and Check Engine light to come on. I took it into a local transmission shop that seems reputable, and they checked all the easy stuff (sensors, etc) and said the problem must be internal, and wound up rebuilding it for $3700. They said it had a bad servo, whatever that means.

After the rebuild, the CEL and AT light weren't on anymore, and all appeared to be well except for a few oddball shifts that I attributed the transmission "relearning". But then around New Years, the AT light came on again, shifts from first to second revved too high, and putting it from park into reverse was a violent affair.

I took it back to the trans shop, still under warranty, and they found that there was a blown fuse. Here's their diagnosis:
"Shifts great 1-5 gears. Cel on. AT light on. Arsh reverse engagement. Scan tool displays no codes in PCM, TCM, and KOER. Install quick scanner. Does not power up. Try another techs scan tool. Indicates it has no power to DLC connector. Check wiring diagram for DLC. Fuse panel under passenger kick panel. Fuse F47 10 mini fuse blown. Replace fuse, still no codes. Start vehicle, all fail lights are off and has normal transmission operations."

Relief, right? Well a few weeks later it started acting up again - Violent shifting into reverse. This time I checked Fuse F47 before bringing it to the shop and it was fine, so I brought it back. They had the pan off, checked a bunch of things but said the solenoids and everything in the pan checked out OK, and it was a wiring problem and not covered by warranty. I told them to halt and that I would take it to the dealer, which I did. Trans shop's notes say:
"Code Po471 TCC performance or stuck off.
P0771 Shift Sol E performance or stuck off.
Clear codes. Immediately come back. Hard fault. All solenoids ohm. Fine through trans connector.
P0745 Shift Sol A hard fault occurred once."

Took it to the dealer and provided them with the above info. Dealer's diagnosis:
Checked and found codes P0745 and P0733. Checked pressure solenoid and shift solenoid 'E'. Tried to actuate solenoids with scan tool, would not actuate. Checked connector at transmission, appears OK. Possible TCM problem. Would like to remove transmission pan and check connections at solenoids, estimate of 1085.00.

Having already spent $3700+, and knowing that they wanted to replace the TCM, I knew I could replace that with relative ease for about $150 so I figured that was worth trying before letting the dealer rack up four-figure charges. I got a TCM from a nearby salvage yard but unfortunately installing a different TCM made no difference.

I can take it back to the transmission shop, who knows the history of this particular car pretty well now but not Mazda3's overall, or I can take it back to the dealer and pay and arm and a leg per hour with no assurance that even thousands of dollars worth of work will result in a fix. Has anyone else come across anything like this? I came across one similar tale on here where the TCM replacement appeared to solve it, but unfortunately that didn't pan out for me...

Shifting into reverse is still rough - I've been driving in such a way so as to avoid using reverse at all times. Downshifts from 5th to 4th can be slightly clunky sometimes, as is coming to a stop. Upshifts are generally good with the exception of 1st to 2nd, where the RPMs sometimes go higher than they should.

Unfortunately I didn't gleam any info from the post above (no responses), but for the benefit of anyone that might have found this page through a web search that is having the same problem, I'm happy to say that the problem appears to be fixed now. It set me back another few hundred but the transmission shop identified a bad connection in one of the connectors. Unfortunately I don't know for sure which one it was, but they were able to fix it by bending some pins to ensure better contact with the harness connectors.

Also, I learned that if you want to try to install at Transmission Control Module, consider carefully how you buy it. I called a local salvage yard (that referred me to a different one that they knew would have it in stock) and bought it for $150 plus shipping. However, I bought it without checking around much and they also told me that I could return it for a 20% restocking fee, which apparently wasn't true in the end. Anyway, you can find them on eBay for $100 right now from numerous sellers. But for me, that wasn't the problem anyway.

Unfortunately this problem continued to happen. They tried tightening up the pins again, and before they even bent anything they were able to get it working again simply by disconnecting the sensor connector from the top of the transmission and reconnecting it, then tightened the pins/sockets again for good measure. It worked fine for a few weeks, then back to its old ways (AT and Check Engine lights on, hard shifts into reverse).

Most recent is that they replaced the "E" solenoid wire. It's still working fine, but if it goes bad again, next step might be to replace the entire wiring harness, which won't be cheap. Not just that connector - The entire harness all over the engine.

I know I'm kind of talking to the wind, but hopefully someone will find this information useful someday.

If I knew then what I know now, I would have traded it in and let the dealer handle it from there.
Having the dealer do the rebuild (or replacing it with a used rebuilt one) would have definitely been more expensive from what I have been able to gather. Would the dealer have had better odds of finding the real problem (the connector/wiring)? Maybe. Who knows. But the dealer also wanted to charge me $1200 to replace the Transmission Control Module, which can be bought on eBay for about $100 and installed in 20 minutes. If they planned to do more within that $1200 blessing, they didn't articulate what else the were going to do.

2004 Mazda 3 transmission problems
Hi, I hope someone can help me. I bought a 2004 mazda 3s, brand new in 2004. It now has 106K miles on it. I previously noiced that when i put the car in reverse (after it sits overnight or while I'm at work) it makes a very loud noise, bangs and jumps. Now all of the sudden, it wont go into 4th gear and when it does, it just revs and wont catch. i tried putting it in manual so i can keep it in 3rd gear, but after a couple minutes the MT Gear indicator that shows what gear I'm in, shuts off and it goes into automatic. is it a computer prob or a transmission problem or both? If anyone can help me or give me advice, i would greatly appreciate it. I appreciate you taking the time to read and reply. I love my mazda and want her back to normal!
-LB

Hi;
My daughter's car 2004 Mazda 3 started a month ago 119,000 Kms would shift really rough in reverse then would shift as far as 3rd would rev up when trying to catch in 4th sometimes would catch other times would rev then AT light and Check engine light would come on, then it would shift down to 2nd even on the highway. I replaced the solenoids then the valve body changed the oil . replaced the Turbine speed sensor , took out the over drive clutches and band and replaced those still same issue getting worst the code was P0762 shift solenoid stuck I am at the end of my rope also with this vehicle and I'm scared that replacing the transmission may not even fix the issue if it's TCM or Harness related. I know what vehicles to stay away from in the future. I'd be interested to know how many people have fallen for the no service transmission info from Mazda? If they can't make a transmission that will last 100,000 miles they may as well quit. I hear their ads about Skyactive they won't be getting any endorsements from here for sure. I think I will start tweeting as well.

my 2006 automatic mazda3 is at 113k miles and the transmission just went.
3500$ to get a rebuilt transmission from mazda, plus another 3000 of work that they say is needed, so they recommend a new car.
gear 1 and 2 are ok, but jumps when in reverse, and the car wont go into 3rd or higher.
still debating trying to fix it.

My 2006 Mazda 3 with 203k on the clock developed the same AT light and Check Engine light warnings and the Mazda dealer determined that the transmission needed replacing, my bank account is $5,200 lighter.

Mazda wanted almost 6k to fix up my 2006 mazda3. But they recommended selling it to
Them for 400$ and buying a new mazda instead. I didn't have the $ for either option so
I called Cottman transmission and they fixed it up for less than 2k. I drive about 2 hours a day
every day and the car runs great now. Cottman told me that Mazda had ended up redesigning 3rd gear because they were having so many problems w the old style. He said they see an awful lot of
Mazda3s in for transmission issues

My wife has a 2004 mazda 3 2.0 auto and have been having alot of these issues.
It was geat at first but so far we have replaced 3 TSS sensors and rebuilt the transmission. Yesterday it wouldnt go in any gears this has all happened in the last year. Im debating if I should try and get it fixed or just sell the car. Any one know if we can use newer transmissions that where better made? Seems like my years was really bad

Hi I am desperately seeking some help. I have been researching and looking for someone with the same symptoms as mine for 2 weeks. I have 2006 Mazda 3 automatic with 127800k miles. From what I have read I'm lucky to not be experiencing major issues until now. I love my Mazda but it is skipping 2nd gear when I brake for about 4 months now. It doesn't seem to shift into the right gears at the right times either. Slight jerking sometimes but not often. It idles really low when at a complete stop. I know I am lucky it still shifts into all 4 gears . My fear is soon it will not. My check engine light and at light was on a few weeks ago the codes led to my mechanic changing a transmission sensor. The lights are both off and have not come back on however the weird shifting is taking place. The rpm needle sometimes drops on its on without me taking my foot of the gas ?? Please help if anyone has experienced this issue . I have no idea what to even have checked out. My mechanic says the deceleration issue is something he's never seen

i am also having the same problem with my mazda 3.. its a 2007 model 2.0. i got the transmission rebuild and about 3 months later still the same problem with the A.T light and hard reverse.. what did you do to get your problem fix.

I haven't looked back at this site for a while but I got an email indicating that tallup was asking for an update. I'm sorry I don't have better news to report to everyone...
As a quick recap, my AT light had come on, the transmission shop checked the usual suspects, and said it must be internal and proceeded to rebuild the transmission. After that, the AT light was initially off but came back on within about a week. I brought it back to them and they said a fuse was blown, they replaced it, and the AT light was off again. It kept coming back on, and I kept bringing it in, and it seemed to be settling on one of the electrical connectors. They replaced that connector, but the light still kept coming on after a few days of driving.

Usually the AT light would come on and the car would drive poorly, but the AT light would not come back on the next time that I started the car. Then eventually it would come on again, usually accompanied by the check engine light the second time, which would stay on until I brought it in again.

Bringing it back each time was a huge hassle, and eventually I tried to figure out how to disconnect and reconnect that sensor myself. I also tried replacing the TCM which made no difference. But then I stumbled upon an easier, though temporary, fix.

Each time that I was disconnecting and reconnecting that sensor, or replacing the TCM, I was taking out the battery. Well it turns out that disconnecting the battery for an hour or so cleared out the codes so the AT light would be off, for another week or so. And the car drives fine whenever the light is off.

Since neither the transmission shop nor the dealer could find the problem, and since the next steps that they were suggesting were outrageously expensive, I instead invested in a five dollar switch for the top of the battery. When the AT light comes on, I ignore it because it'll go off on its own next time I start the car. When it comes on the second time, I turn the battery switch when I park the car, usually overnight.

It resets my clock and radio presets, so that's annoying, but a $5 sure fix definitely beats a $5000 gamble on another repair.

ok..i see your mazda is giving you some trouble... I saw post online and some guys changed their solenoid and their problem disappeared... i think you should try changing your solenoid and harness as well and see if your problem goes away.. my vehicle is currently @ the mechanic and he is changing the solenoid to see if the problem goes away. When he is finish with it I will keep you guys updated.... i am also finding it strange your switch is working for you somewhat.